title: An outbreak of Sarcocystis calchasi encephalitis in multiple psittacine species within an enclosed zoological aviary.
abstract: A total of 5 psittacine birds in an enclosed zoological exhibit, including 2 princess parrots and 3 cockatoos of 2 different species, developed severe central nervous system clinical signs over a 2-3-month period and died or were euthanized. Histologically, all birds had a lymphoplasmacytic and histiocytic encephalitis with intralesional protozoa consistent with a Sarcocystis species in addition to intramuscular tissue sarcocysts. By immunohistochemical staining, merozoites in brain and tissue cysts in muscle did not react with polyclonal antisera against Sarcocystis falcatula, Sarcocystis neurona, Toxoplasma gondii, and Neospora caninum, or with a monoclonal antibody to S. neurona. Transmission electron microscopy on sarcocyst tissue cyst walls from 2 birds was morphologically consistent with Sarcocystis calchasi. Polymerase chain reaction (PCR) amplification and sequencing of partial 18S ribosomal RNA from muscle tissue cysts and brain schizonts from 3 birds was consistent with a clade containing S. calchasi and Sarcocystis columbae but could not distinguish these closely related Sarcocystis species. However, PCR amplification and sequencing of the internal transcribed spacer 1 RNA segment in the brain from 2 birds and muscle from 2 birds specifically identified the isolates as S. calchasi. The current report documents that multiple psittacine species are susceptible intermediate hosts of S. calchasi, and that infection can cause encephalitis resulting in significant morbidity and mortality in psittacine aviaries.
authors.affiliation: 1Guillermo Rimoldi, Animal Health and Food Safety Laboratory System, Davis Branch, Davis, CA 95616. grimoldi@cahfs.ucdavis.edu.
authors.forename: Guillermo
authors.initials: G
authors.lastname: Rimoldi
authors.forename: Brian
authors.initials: B
authors.lastname: Speer
authors.forename: James F X
authors.initials: JF
authors.lastname: Wellehan
authors.forename: Daniel S
authors.initials: DS
authors.lastname: Bradway
authors.forename: Lewis
authors.initials: L
authors.lastname: Wright
authors.forename: Drury
authors.initials: D
authors.lastname: Reavill
authors.forename: Bradd C
authors.initials: BC
authors.lastname: Barr
authors.forename: April
authors.initials: A
authors.lastname: Childress
authors.forename: H L
authors.initials: HL
authors.lastname: Shivaprasad
authors.forename: Richard P
authors.initials: RP
authors.lastname: Chin
mesh_terms: D000818:Animals; D000836:Animals, Zoo; D001483:Base Sequence; D001715:Bird Diseases / Q000469:parasitology* / Q000473:pathology; D002493:Central Nervous System Diseases / Q000469:parasitology / Q000473:pathology / Q000662:veterinary*; D016054:DNA, Protozoan / Q000737:chemistry / Q000235:genetics; D004196:Disease Outbreaks / Q000662:veterinary; D017809:Fatal Outcome; D007150:Immunohistochemistry / Q000662:veterinary; D046529:Microscopy, Electron, Transmission; D008969:Molecular Sequence Data; D010311:Parrots; D010802:Phylogeny; D016133:Polymerase Chain Reaction / Q000662:veterinary; D012337:RNA, Ribosomal, 18S / Q000737:chemistry / Q000235:genetics; D012522:Sarcocystis / Q000235:genetics / Q000302:isolation & purification* / Q000648:ultrastructure; D012523:Sarcocystosis / Q000469:parasitology / Q000473:pathology / Q000662:veterinary*; D016415:Sequence Alignment; D017422:Sequence Analysis, DNA
chemical_list: D016054:DNA, Protozoan; D012337:RNA, Ribosomal, 18S
keywords: Aviary; Sarcocystis calchasi; encephalitis; psittacines